Polyethylene glycol (PEG) induced protoplast fusion is the most commonly used as it induces reproducible high frequency fusion accompanied with low toxicity to most cell types. The protoplast mixture is treated with 28-50% PEG (MW 1,500-6,000) for 15-30 min, followed by gradual washing of the protoplasts to remove PEG; protoplast fusion occurs during the washing.

The washing medium may be alkaline (pH 9-10) and contain a high Ca2+ ion concentration (50 m moll-I); this approach is a combination of PEG and high pH-high Ca2+ treatments, and is usually more effective than either treatment alone. PEG is negatively charged and may bind to cations like Ca2+, which, in turn, may bind to the negatively charged molecules present in plasma lemma; they can also bind to cationic molecules of plasma membrane.

The high voltage creates transient disturbances in the organisation of plasma lemma, which leads to the fusion of neighbouring protoplasts. The entire operation is carried out manually in a specially designed equipment, called electroporator. Many workers feel that this fusion technique is more desirable than the others for a number of important reasons.